This invention relates to synchronizing audio signal samples taken at different sampling rates.
Commonly assigned McPherson et al. U.S. patent application Ser. No. 09/066,042, filed Apr. 24, 1998 and Thagard et al. U.S. patent application Ser. No. 09/066,043, filed Apr. 24, 1998 are incorporated herein by reference.
Technology of the type used for software carriers such as the Digital Versatile Disc ("DVD") makes it economically viable to provide recording media containing greatly enhanced audio information. For example, it is possible to provide digital audio recordings on such software carriers having multiple channels of digital audio to be played by six-channel audio systems. The typical multiple-channel audio system has a front left channel, a front center channel, a front right channel, a rear left channel, a rear right channel, and a subwoofer channel.
It is known that increased sampling rates provide better audio reproduction. However, sampling all channels of multi-channel audio at very high rates may produce more data and take up more space on the software carrier than is necessary to produce better reproduction. For example, the information in the front channels of six-channel audio tends to be more important than the information in the rear and subwoofer channels. It may therefore be adequate to sample only the front channels at the highest rate, while the rear and subwoofer channels are sampled at lower rates. This reduces the amount of data that needs to be stored on the software carrier (as compared to sampling all channels at a very high rate) and therefore saves space on the software carrier.
A possible problem with sampling different channels at different rates is that it increases the difficulty of maintaining synchronization and proper phasing between all the channels, especially when the data stream is modified for such purposes as editing and splicing different portions of the data stream together.
In view of the foregoing, it is an object of this invention to provide improved synchronization of audio signal samples taken at different sampling rates.